The present series of inventions was prompted by the obvious need to decrease the exposure of healthcare workers to potentially harmful needle sticks which, as detailed in the inventors' recent disclosure (U.S. Pat. No. 5,478,328 in 1995), pose the risk of infection with diseases such as hepatitis and AIDS. All too commonly, inadvertent needle sticks occur with needles that are being used for, or have been used for, penetrating a diaphragm. The varied uses of such needle/diaphragm combinations include: (a) withdrawing from or injecting into a medication vial, collection tube, or fluid bag; (b) injecting or withdrawing medications or fluids via tubing attached to an intravenous catheter.
The common features of the present series of inventions include needle/diaphragm combinations wherein:
(a) "safe yet penetrating" needles, such as those illustrated, in part, in our prior patent (U.S. Pat. No. 5,478,328) and claimed herein, are designed to provide a compromise between "penetrating but dangerous" sharp needles of traditional systems and newer "safe but nonpenetrating" blunt cannulae of needleless blunt-cannula systems (described below). The inventive needles are designed to decrease the likelihood of harmful puncture of the skin of a healthcare worker (compared to that associated with a traditional needle) by one or both of the following: PA1 (b) the "strong yet penetrable" diaphragms of the present disclosures are a compromise between the "strong but (relatively) impenetrable" and the "penetrable but weak" extremes described in the prior art (described below). They are designed to: PA1 1. Strong Diaphragm/Dangerous Needle --It traditionally was felt that, in virtually all settings, needle insertion through a diaphragm necessitated the use of a sharp needle. Known hypodermic needles for use with penetrating diaphragms typically have: PA1 2) Weak Diaphragm/Safe Cannula --The newly designed "needleless" blunt-cannula systems (e.g., the InterLink System, Baxter Healthcare Corp., Deerfield, Ill. in collaboration with Becton-Dickinson Co., Franklin Lakes N.J.; and the Lifeshields system, Abbott Laboratories, Abbott Park Ill.) contain a diaphragm that is modified at the time of manufacture to such a degree that it is penetrable by an "absolutely" blunt-tipped cannula (with an end that typically is 0.degree. (flat) or hemispherical, and never with &gt;15.degree. angle to the longitudinal axis of the cannula shaft). The manufacture of the diaphragm (herein called a "blunt-cannula diaphragm") has been taught within the prior decade as follows: PA1 a) Because they require an appreciable degree of prechannelling or weakening at the time of manufacture, they have not been recommended for prolonged drug storage even prior to first clinical use and especially after they have been penetrated by a needle or cannula. Even in the prior art configuration in which the preslit extends only partway through the blunt-cannula diaphragm, "the end of the blunt cannula will be used to tear through the remainder of the sealing member." (WO 90/11103) This necessitates a very weak "tearable" portion which may restrict shelf-life, and it leads to the potential for poor resealing as a result of the tearing process. This has led to modifications such as the two stopper members and ferrule described above (Hooks U.S. Pat. No. 5,328,041) or an extra valve which serves to reinforce the potentially incompetent site of needle/cannula entry and thereby reduce the risk of leakage (Brimhall U.S. Pat. No. 5,242,393). Despite these modifications, bottles and bags that either house or transfer medication and/or fluids for extended periods of time typically are not equipped for use with the Baxter or Abbott blunt-cannula systems. PA1 b) It is recommended that such blunt-cannula diaphragms be used only with specially designed blunt cannulae since they are prone to damage by sharp needles. Said cannulae have been described as having distal ends which are completely blunt (0.degree. degree angle to the longitudinal axis), arcuate, or hemispherical or as having a lead post which extends beyond the end of the cannula (to guide insertion) or a taper with up to a 15.degree. angle to the longitudinal axis. Greater tapers and actual points were avoided in large part because of the preslit/preweakened diaphragm's susceptibility to damage. The inventors of needleless systems also proposed the use of conventional lubricant "to further reduce the friction and lower the insertion force required." (WO 90/11103) PA1 c) The blunt-cannula diaphragms only can accept blunt cannulae of limited diameter and the diaphragm itself cannot be provided in the widths required to cover variously sized bottle tops, injection ports, and collection tubes without unacceptably compromising diaphragm integrity. As stated by the inventors (WO 90/11103) of the blunt-cannula system: "To provide for leak-free insertion, the length of the slit in the sealing member must be less than one-half the circumference of the cannula being inserted therethrough [--as a consequence of the greater penetrating ability of our inventive needles, the length of the slit would not so severely limit the diameter of the fluid channel when the proposed inventive needles are used] . . . In addition, the slit length must be great enough, given the elastic limit of the sealing member, to prevent tearing during insertion."[-- again, this should be less of a problem when a more tapered device (e.g., inventive needle) is used]. PA1 d) In order to accommodate a blunt cannula, the preslit typically extends to the surface or an indentation is produced so as to facilitate blunt cannula insertion. Either of these surface modifications may limit the effectiveness of antiseptic swabbing. Attempts to overcome this problem have entailed the addition of a potentially costly step in the manufacturing process, including covering the preslit stopper with a second member (which is to be torn by the blunt cannula). PA1 (a) a partially blunted "safe" tip which is sharp enough to puncture the inventive diaphragm but not sharp enough to penetrate the skin under normal clinical conditions, including incidental contact or contact during recapping; PA1 (b) a closed tip and one or more recessed orifices to minimize exposure to a sizable inoculum should superficial skin penetration occur. The increased safety afforded by the closed tip allows for the safe use of needles which are significantly more pointed than the blunt cannula of needleless systems and thus usable with a wider range of diaphragms and in a wider range of lengths and diameters. In addition, the solid tip lacks the "cutting" quality of an open-tip design and thereby should allow for more effective leak-free engagement and resealing. Moreover, to date, all reported transmissions of AIDS via puncture wounds to healthcare workers have resulted from puncture with a hollow bore device such as a traditional hypodermic needle or a broken glass tube. These present a sizeable inoculum which may be avoided with the solid-tip needles described herein.
1) lessening the pointedness of the tip; PA2 2) providing one or more recessed orifices as opposed to an open tip; PA2 1) provide an intact covering or plug with a section that, at the time of clinical use, can be pierced with greater penetrability than a conventional diaphragm (which requires penetration by a traditional "penetrating but dangerous" sharp-tip needle); PA2 2) have the integrity and long-term shelf-life approximate to that of a conventional diaphragm and thus maintain the sterility of the enclosed contents for months or years prior to the first clinical usage of the needle/diaphragm combination; PA2 3) have the versatility of a conventional diaphragm (i.e., be able to cover openings with a wide range of diameters as may be found on injection ports, bottle tops, etc.); PA2 4) provide a snug, secure fit for the needle or cannula which pierces it and thereby prevent leakage and dislodgement; PA2 5) provide resealing properties after needle or cannula removal that enable the diaphragm to maintain its integrity and hence the sterility of the underlying contents for a satisfactory duration. PA2 (a) a sharp point; PA2 (b) an open tip. Such needles have cutting points, formed by a beveled cut typically at an angle of approximately 45.degree. (or more) to the longitudinal axis of the needle shaft with an opening created at the junction of the beveled edge and the needle bore. Unfortunately, these features pose a threat to anyone who comes into contact with a used needle. The sharp point increases the likelihood of skin puncture; as evidenced by the large number of injuries, relatively little force is needed to penetrate the skin during an inadvertent stick with a sharp needle. The open tip can house infected fluid or tissue (herein called an inoculum); this increases the likelihood that a needle stick will result in disease transmission. The sharp-point, open-tip construction not only increases the risk of injury to a healthcare worker during usage but also increases the likelihood of accidental injury during recapping as a consequence of missing the cap or actually piercing the side of the cap. PA2 (a) cutting a slit into the central portion of the diaphragm with a knife ("preslitting") (Jepson, Dudaran, and Finley WO89/06553 & WO90/11108 in 1989/90 --Baxter). PA2 (b) reinforcing such a preslit diaphragm by covering the main plug with a thin diaphragm portion and using a metal ferrule which remains permanently in place for securing the inner and outer members of the stopper assembly together (Hook U.S. Pat. No. 5,328,041 in 1994 --Abbott). In justifying the need for his more complex process (which includes two stopper members and a ferrule), the inventor stated that this was required to maintain sterility of the contents of vials covered with a preslit diaphragm: "the same prepierced construction used in prepierced reseals cannot be implemented for the stoppers on vials because of sterility and shelf-life degradation questions." PA2 (c) molding the diaphragm in two pieces which are joined by a penetrable hinged region (Grabenkort U.S. Pat. No. 5,403,293 in 1995 --Abbott). Although Grabenkort claimed that his method of "compression molding allows the tolerances at the hinged region to be better controlled than the alternate method of cutting a slit into a rubber diaphragm (as originally described in a patent assigned to Baxter), the procedure to accomplish this appears to be more complicated as it involves the production of a stiff annular collar having a first and second annular flange. PA2 (d) using ultrasonic heating to create a weakened portion that extends at least partially through the diaphragm's midsection. The horn and anvil of the mounting device conduct heat away from the outer surfaces, thereby allowing them to remain continuous and unbroken (Helgren U.S. Pat. No. 5,403,525 in 1995 --Abbott).
Disclosure #II of the three-part series introduces the concept of and means of a "converting" mechanism for modifying the diaphragm immediately prior to its first penetration for clinical use. This converts a strong diaphragm which otherwise would not be so readily penetrable by a given "safe" needle or cannula to a diaphragm which can be used in combination with said needle or cannula.
Disclosure #III of the three-part series introduces the concept of and means of providing reversible compression of a prechannelled or preweakened diaphragm. This enables one to ensure effective closure of a preslit or preweakened region before a diaphragm has been penetrated by a needle or cannula and, in many embodiments, restoration of the ancillary pressure secures effective closure even after penetration.
As alluded to above, prior to the present invention, two extremes of needle/diaphragm combinations have been available: 1) Strong Diaphragm/ Dangerous Needle; or 2) Weak Diaphragm/Safe Cannula. These are described below:
Review of the earlier prior art shows that the use of a more readily penetrable diaphragm was taught 30 years previously, but none of the inventions of the prior art was designed to facilitate passage of a "safe" needle as described in the present invention. Wimmer (U.S. Pat. No. 3,653,528) taught a means of creating an indentation in the outer surface to facilitate piercing without coring by a standard hypodermic needle. Sandhage (U.S. Pat. No. 2,906,423 in 1959) described a preslit diaphragm which was puncturable by a round-tip plastic "needle" which was so blunt that it was also able to be inserted into the teat of a cow to inject medication for the treatment of mastitis; however, this required lubricant to "fill up the cut slit" after needle entry "to aid in preventing the entry of contaminant organisms." Ogle (U.S. Pat. No. 5,060,812) described diaphragms which were modified to such a degree that they were penetrable by a syringe tip or nozzle (as opposed to a needle or cannula). Garrett (U.S. Pat. No. 4,197,848 in 1980) described a resilient, impermeable membrane for a urinary irrigation system, wherein said membrane had a normally closed, resiliently deformable slit. Said slit was maintained closed by compression, but was penetrable by the blunt end of a syringe. Baxter, the assignee of that invention, noted in a subsequent disclosure (WO 90/11103) that there was still a need for a preslit injection site which "will reliably reseal . . . ."
Although the blunt-cannula diaphragms of the Baxter and Abbott needleless systems tend to self-seal after blunt cannula insertion, they do not guarantee adequate shelf-life and sterility in all contexts:
The absolutely blunt cannulae of the Baxter and Abbott needleless systems also pose limitations. As stated above, they can be of only limited diameter (and thus can allow only limited flow rates) as they would otherwise require an unacceptably large slit in the diaphragm to allow insertion of their blunt tip. In addition, they tend to slip out of the blunt-cannula diaphragm, a problem that could be partially mitigated by increasing cannula length, but such a change would slow flow even further. Realizing the potential problems associated with a standard blunt cannula system, the inventors (WO 90/11103) note: "In accordance with further aspects of this invention, the blunt cannula may be provided with features that facilitate insertion into the injection site, enhance fluid flow or dispersion, increase tug resistance, and reduce kickback." These include: 1) the inclusion of a plurality of elongate discharge slits to improve flow which otherwise may be compromised by the cannula's narrow diameter as well as to decrease the contact surface area so as to facilitate insertion; 2) grooves on the side of the cannula to reduce surface area; 3) a lead post to guide cannula insertion; 4) annular barbs to reduce kickback; 5) matching locking means, gripping means, and "retaining fingers" to secure engagement. Moreover, the use of blunt cannulae necessitates modification or replacement of existing setups, so that a blunt-cannula diaphragm is always available. The use of the prior art blunt cannula in the absence of a setup with a preslit or weakened diaphragm is virtually impossible unless one inserts a special "spike" adaptor. One side of the adaptor has a sharply pointed, open-tipped spike which can pierce a standard diaphragm; the other side has a preslit diaphragm. The spike must remain in place as long as the blunt cannula is used; and it must be discarded as a potentially hazardous sharp object (akin to a "penetrating but dangerous" needle) once it is no longer required. To the best of our knowledge, there has been no attempt to increase cannula penetrating properties in a manner comparable to that of the present disclosure; i.e., there has been no obvious attempt to increase penetrating capabilities by using a tapered needle (such as those claimed in the present three-part series) and thereby allowing for an inherently stronger entry point in the diaphragm.
The limitations of needleless systems are significant to the degree that the New York State Study on Needlestick Prevention Devices (in 1992) reported that two-thirds of healthcare workers felt that special training in the use of a needleless device was required and 20.3% of the workers at a major test center believed delivery was impeded with the device. Furthermore, the report noted that, because of the inability to provide blunt- cannula diaphragms for most containers (e.g. bottles, bags), ". . . needles used with the system continued to be a hazard for injury. In one institution, needles continued to be used for administering heparin or saline `flushes` while in the other hospital, in an attempt to avoid this hazard, a complicated system using multiple components was put into place." These factors led the compilers of the NYS report to conclude that blunt-cannula systems are less cost-effective than systems using traditional sharp, open-tipped needles enclosed in a plastic shield; thus, although they do not eliminate the potential to contact a dangerous needle, the report concluded that shielded needle systems produce "greater reductions in needlestick injuries" than the needleless systems. Of note, neither the NYS Study nor an Apr. 16, 1992 FDA Safety Alert ("Needlestick and other risks from hypodermic needles on secondary i.v. administration sets") recommended or even mentioned the use of an intrinsically safer needle (as opposed to a "safe but nonpenetrating" blunt cannula or a "penetrating but dangerous" sharp needle which is extrinsically modified with a shield). This provides strong evidence that the subject-matter disclosed herein, and in the applications and patents incorporated by reference, was not apparent even to experts and leaders in this field.